Use the information and your knowledge of climate, global systems, and ecosystem interactions to help you
answer the following five questions.
Something very interesting happened to the climate of
the West Coast of the United States after the last ice
age, which occurred about 10,000 years ago. Before
the ice age, the Southwest United States had an
abundance of plant life and was home to large fauna
such as saber-tooth cats and mammoths. The Pacific
Northwest was mostly grasslands.
After the ice age, the jet stream that was responsible
for pushing wind and moisture to the Southwest
shifted north as the glaciers retreated, and showered
the Pacific Northwest with precipitation. This led to the
dense forests that now cover that region, and a drying-
out of the Southwest.
1. How is climate defined? Do the events described
constitute a change in climate for the West Coast
of the United States?
2. View the current climate chart for Yuma, Arizona,
which is located in the Southwestern United
States. What changes would you make to model
the climate before the ice age? Explain why you
would make these changes.
Yuma, Arizona
400
300
200
Avg. Temperature (°C)
40
30
20
10
0
-10
-20
-30
Avg. Precipitation (mm)
100
0
JFMAM J J A SOND
Month